We studied the electronic and magnetic properties for the Mn-doped chalcopyrite AlGaP2 semiconduc... more We studied the electronic and magnetic properties for the Mn-doped chalcopyrite AlGaP2 semiconductor by using the first-principles calculations. The Mn-doped AlGaP2 yields strong half-metallic ground states. The ferromagnetic state is the most energetically favorable one. The states of host Al, Ga, or P atoms at the Fermi level are mainly a P-3p character, which mediates a strong interaction between the Mn-3d and P-3p states. The ferromagnetic ordering of dopant Mn with high magnetic moment is originated from the P(3p)-Mn(3d)-P(3p) hybridization, which is attributed by the partially filled P-3p bands. The high magnetic moment of Mn by P vacancy is produced by 4.2 B/Mn.
Single phase AlCrN thin films were obtained. The lattice parameter of the a-axis increased while ... more Single phase AlCrN thin films were obtained. The lattice parameter of the a-axis increased while the lattice parameter of the c-axis decreased with an increase of Cr content. Within the doping limit, the saturated magnetization increased with increasing of Cr content. All the samples shows strongly ferromagnetic properties. The ferromagnetic properties is very strong compared to reported value.
We study the structural stability and magnetic properties for 3d transition-metal thin films on C... more We study the structural stability and magnetic properties for 3d transition-metal thin films on Cu(100) by a detailed ab initio calculation. The diffusion of Ni atoms into the bulk is energetically more favorable than the formation of cluster at the surface. For the 1-3 monolayer (ML) thick CuNi surface alloy on Cu, we demonstrate that the subsurface formation of 1-ML, 2-ML, or 3-ML thick Ni films below a Cu cap layer is energetically a more favorable structure. Our result of the energetics of surface alloying is in good agreement with the recent LEED experiment and other theoretical results.
The effects on the ferromagnetism of a nitrogen defect in Cu-doped AlN with a Cu concentration of... more The effects on the ferromagnetism of a nitrogen defect in Cu-doped AlN with a Cu concentration of 2.77-8.33% have been investigated by first-principles. For Al Cu N, a global magnetic moment of 1.46 /cell, with a localized magnetic moment of 0.75 /Cu is found. The formation of Cu-Cu in AlN with the N vacancy is more energetically favorable than that without the. Hence, the state is produced easily. The Cu magnetic moment of Cu-Cu pair becomes very low by the weak 3d-3d spin coupling due to the spin-exchange interaction between Cu-3d and N defect states.
We investigate the electronic and magnetic properties in Cu-doped InN with the N vacancy (V N) fr... more We investigate the electronic and magnetic properties in Cu-doped InN with the N vacancy (V N) from first principles calculations. There is the long-range ferromagnetic order between two Cu atoms, attributed to the hole-mediated double exchange through the strong p-d interaction between the Cu atom and neighboring N atom. The system of V N defect in Cu-doped InN has the lowest formation energy. Due to the hybridization between the Cu-3d and V N states, the spin-polarization on the Cu atoms in the InN lattice is reduced by V N defect. So, it shows a weak ferromagnetic behavior.
We study the energetics and magnetism for 3d transition-metal (TM) thin film on Cu(0 0 1) by a de... more We study the energetics and magnetism for 3d transition-metal (TM) thin film on Cu(0 0 1) by a detailed ab initio calculations. For 1-ML 3d TM on the Cu(0 0 1) substrate, we find the interaction between Ni and Cu atoms at the interface shows attraction, while the Fe-Cu interaction shows repulsion. At a coverage of 0.5 Ni ML, we find that an ordered ferromagnetic (2Â2) surface alloy is not formed. For the 1-2-ML Ni films on Cu we demonstrate the energetically favorable structure in the case of several surface alloy including the coverage of 0.5 ML in (or below) the surface layer. Our ab initio results for the energetics of surface alloying are in agreement with LEED experiment.
The electronic property and the magnetism of AlGaMnP2 compound by 3.125 %, 6.25 %, and 9.375 % Mn... more The electronic property and the magnetism of AlGaMnP2 compound by 3.125 %, 6.25 %, and 9.375 % Mn concentrations were investigated using the first-principles calculations. The Mn-doped AlGaP2 chalcopyrite with or without defect of Al, Ga, or P atom yields a strong half-metallic ground state. The ferromagnetic state is the most energetically favorable one. The spin-polarization of Mn dopant is stable with a magnetic moment close to 4B due to intra-atomic exchange coupling. The states of host Al, Ga, or P atoms at the Fermi level are mainly a P-3p character, which mediates a strong interaction between the Mn-3d and P-3p states. The ferromagnetic state with high magnetic moment is originated from the hybridized P(3p)-Mn(3d)P(3p) interaction formed through the p-d coupling without the defects. It is noted that the ferromagnetism arises from two distinguishing characteristics by polarons and by holes-mediated exchange-coupling.
2016 International Conference of Asian Union of Magnetics Societies (ICAUMS)
The AlGaP ternary material is used in devices such as visible light-emitting diodes, laser diodes... more The AlGaP ternary material is used in devices such as visible light-emitting diodes, laser diodes, heterojuction bipolar transistors, and so on [1]. The opportunities of spintronics applications have limited due to the low solubility of magnetic ions in non-magnetic semiconductor hosts. Diluted Magnetic Semiconductor (DMS) possess interesting magnetic behaviour arising due to the replacement of small amount of host anion by magnetic impurity. For the realization of DMS materials in practical applications, they should exhibit room temperature ferromagnetic ordering. When ferromagnetic metals are used as spin injectors, the polarization in the semiconductor tends to be quickly lost via spin-flip scattering. It is one of the primary challenges to create the ferromagnetic semiconductors due to the difficulty in the spin-injection into the semiconductors to form DMS at room temperature.
We studied the electronic and magnetic properties for the Mn-doped chalcopyrite (CH) AlAs, GaAs, ... more We studied the electronic and magnetic properties for the Mn-doped chalcopyrite (CH) AlAs, GaAs, and AlGaAs2 semiconductor by using the first-principles calculations. The chalcopyrite AlGaP2, AlGaAsP, and AlGaAs2 compounds have a semiconductor characters with a small band-gap. The interaction between Mn-3d and As-4p states at the Fermi level dominate rather than the other states. The ferromagnetic ordering of dopant Mn with high magnetic moment is induced due to the Mn(3d)-As(4p) strong coupling, which is attributed by the partially filled As-4p bands. The holes are mediated with keeping their 3d-electrons, therefore the ferromagnetic state is stabilized by this double-exchange mechanism. We noted that the ferromagnetic state with high magnetic moment is originated from the hybridized As(4p)-Mn(3d)-As(4p) interaction mediated by the holes-carrier.
The effects on the ferromagnetism of the O or Zn defect in Cu-doped ZnO with the concentration of... more The effects on the ferromagnetism of the O or Zn defect in Cu-doped ZnO with the concentration of 2.77-8.33% have been investigated by the first-principles calculations. The Cu doping in ZnO was calculated to be a kind of p-type ferromagnetic half-metals. When the Zn vacancy exists in Cu-doped ZnO, the Cu magnetic moment increases, while for the O vacancy it is reduced. It is noticeable that the ferromagnetic state was originated from the hybridized O(2p)-Cu(3d)-O(2p) chain formed through the p-d coupling. The carrier-mediated ferromagnetism by nitrogen or fluorine does not depend on their concentration.
The effects on the ferromagnetism of the O or Zn defect in Cu-doped ZnO with the concentration of... more The effects on the ferromagnetism of the O or Zn defect in Cu-doped ZnO with the concentration of 2.77-8.33% have been investigated by the first-principles calculations. The Cu doping in ZnO was calculated to be a kind of p-type ferromagnetic half-metals. When the Zn vacancy exists in Cu-doped ZnO, the Cu magnetic moment increases, while for the O vacancy it is reduced. It is noticeable that the ferromagnetic state was originated from the hybridized O(2p)-Cu(3d)-O(2p) chain formed through the p-d coupling. The carrier-mediated ferromagnetism by nitrogen or fluorine does not depend on their concentration.
We studied the effect on the electronic and magnetic properties of the N defect in clean and Cu-d... more We studied the effect on the electronic and magnetic properties of the N defect in clean and Cu-doped wurtzite III-nitrides by using the first-principles calculations. When it is doped two Cu atoms in the nearest neighboring sites, the system of AlN, GaN, or InN with the N vacancy is energetically more favorable than that without the N vacancy site. When the Cu concentration increases, the total magnetic moment of a supercell becomes small. The ferromagnetism of Cu atom is very low due to the weak 3d-3d coupling. It is noticeable that the spinexchange interaction between the Cu-3d and N defect states is important.
The electronic structure and magnetic properties of chalcopyrite (CH) AlGaAs 2 with dopant Mn at ... more The electronic structure and magnetic properties of chalcopyrite (CH) AlGaAs 2 with dopant Mn at 3.125 and 6.25 % concentrations are investigated using first-principles calculations. The CH AlGaAs 2 alloy is a p-type semiconductor with a small band-gap. The AlGaAs 2 :Mn shows that the ferromagnetic (FM) state is the most energetically favorable one. The Mn-doped AlGaAs 2 exhibits FM and strong half-metallic ground states.The spin polarized Al(Ga,Mn)As 2 state (Al-rich system) is more stable than the (Al,Mn)GaAs 2 state (Ga-rich system), which has a magnetic moment of 3.82m B /Mn. The interaction between Mn-3d and As-4p states at the Fermi level dominates the other states.The states at the Fermi level are mainlyAs-4p electrons, which mediate strong interaction between the Mn-3d and As-4p states. It is noticeable that the FM ordering of dopant Mn with high magnetic moment originates from the As(4p)-Mn(3d)-As(4p) hybridization, which is attributed to the partially unfilled As-4pbands. The high FM moment of Mn is due to the double-exchange mechanism mediated by valence-band holes.
The ferromagnetic and electronic structure for the Al x Ga 1-x P and Mn-doped AlGaP 2 was studied... more The ferromagnetic and electronic structure for the Al x Ga 1-x P and Mn-doped AlGaP 2 was studied by using the self-consistent full-potential linear muffin-tin orbital method. The lattice parameters of un-doped Al x Ga 1-x P (x = 0.25, 0.5, and 0.75) were optimized. The band-structure and the density of states of Mn-doped AlGaP 2 with or without the vacancy were investigated in detail. The P-3p states at the Fermi level dominate rather than the other states. Thus a strong interaction between the Mn-3d and P-3p states is formed. The ferromagnetic ordering of dopant Mn with high magnetic moment is induced due to the (Mn-3d)-(P-3p)-(Mn-3d) hybridization, which is attributed by the partially filled P-3p bands. The holes are mediated with keeping their 3d-characters, therefore the ferromagnetic state is stabilized by this double-exchange mechanism.
We studied the electronic and magnetic properties for the Mn-doped chalcopyrite AlGaP2 semiconduc... more We studied the electronic and magnetic properties for the Mn-doped chalcopyrite AlGaP2 semiconductor by using the first-principles calculations. The Mn-doped AlGaP2 yields strong half-metallic ground states. The ferromagnetic state is the most energetically favorable one. The states of host Al, Ga, or P atoms at the Fermi level are mainly a P-3p character, which mediates a strong interaction between the Mn-3d and P-3p states. The ferromagnetic ordering of dopant Mn with high magnetic moment is originated from the P(3p)-Mn(3d)-P(3p) hybridization, which is attributed by the partially filled P-3p bands. The high magnetic moment of Mn by P vacancy is produced by 4.2 B/Mn.
Single phase AlCrN thin films were obtained. The lattice parameter of the a-axis increased while ... more Single phase AlCrN thin films were obtained. The lattice parameter of the a-axis increased while the lattice parameter of the c-axis decreased with an increase of Cr content. Within the doping limit, the saturated magnetization increased with increasing of Cr content. All the samples shows strongly ferromagnetic properties. The ferromagnetic properties is very strong compared to reported value.
We study the structural stability and magnetic properties for 3d transition-metal thin films on C... more We study the structural stability and magnetic properties for 3d transition-metal thin films on Cu(100) by a detailed ab initio calculation. The diffusion of Ni atoms into the bulk is energetically more favorable than the formation of cluster at the surface. For the 1-3 monolayer (ML) thick CuNi surface alloy on Cu, we demonstrate that the subsurface formation of 1-ML, 2-ML, or 3-ML thick Ni films below a Cu cap layer is energetically a more favorable structure. Our result of the energetics of surface alloying is in good agreement with the recent LEED experiment and other theoretical results.
The effects on the ferromagnetism of a nitrogen defect in Cu-doped AlN with a Cu concentration of... more The effects on the ferromagnetism of a nitrogen defect in Cu-doped AlN with a Cu concentration of 2.77-8.33% have been investigated by first-principles. For Al Cu N, a global magnetic moment of 1.46 /cell, with a localized magnetic moment of 0.75 /Cu is found. The formation of Cu-Cu in AlN with the N vacancy is more energetically favorable than that without the. Hence, the state is produced easily. The Cu magnetic moment of Cu-Cu pair becomes very low by the weak 3d-3d spin coupling due to the spin-exchange interaction between Cu-3d and N defect states.
We investigate the electronic and magnetic properties in Cu-doped InN with the N vacancy (V N) fr... more We investigate the electronic and magnetic properties in Cu-doped InN with the N vacancy (V N) from first principles calculations. There is the long-range ferromagnetic order between two Cu atoms, attributed to the hole-mediated double exchange through the strong p-d interaction between the Cu atom and neighboring N atom. The system of V N defect in Cu-doped InN has the lowest formation energy. Due to the hybridization between the Cu-3d and V N states, the spin-polarization on the Cu atoms in the InN lattice is reduced by V N defect. So, it shows a weak ferromagnetic behavior.
We study the energetics and magnetism for 3d transition-metal (TM) thin film on Cu(0 0 1) by a de... more We study the energetics and magnetism for 3d transition-metal (TM) thin film on Cu(0 0 1) by a detailed ab initio calculations. For 1-ML 3d TM on the Cu(0 0 1) substrate, we find the interaction between Ni and Cu atoms at the interface shows attraction, while the Fe-Cu interaction shows repulsion. At a coverage of 0.5 Ni ML, we find that an ordered ferromagnetic (2Â2) surface alloy is not formed. For the 1-2-ML Ni films on Cu we demonstrate the energetically favorable structure in the case of several surface alloy including the coverage of 0.5 ML in (or below) the surface layer. Our ab initio results for the energetics of surface alloying are in agreement with LEED experiment.
The electronic property and the magnetism of AlGaMnP2 compound by 3.125 %, 6.25 %, and 9.375 % Mn... more The electronic property and the magnetism of AlGaMnP2 compound by 3.125 %, 6.25 %, and 9.375 % Mn concentrations were investigated using the first-principles calculations. The Mn-doped AlGaP2 chalcopyrite with or without defect of Al, Ga, or P atom yields a strong half-metallic ground state. The ferromagnetic state is the most energetically favorable one. The spin-polarization of Mn dopant is stable with a magnetic moment close to 4B due to intra-atomic exchange coupling. The states of host Al, Ga, or P atoms at the Fermi level are mainly a P-3p character, which mediates a strong interaction between the Mn-3d and P-3p states. The ferromagnetic state with high magnetic moment is originated from the hybridized P(3p)-Mn(3d)P(3p) interaction formed through the p-d coupling without the defects. It is noted that the ferromagnetism arises from two distinguishing characteristics by polarons and by holes-mediated exchange-coupling.
2016 International Conference of Asian Union of Magnetics Societies (ICAUMS)
The AlGaP ternary material is used in devices such as visible light-emitting diodes, laser diodes... more The AlGaP ternary material is used in devices such as visible light-emitting diodes, laser diodes, heterojuction bipolar transistors, and so on [1]. The opportunities of spintronics applications have limited due to the low solubility of magnetic ions in non-magnetic semiconductor hosts. Diluted Magnetic Semiconductor (DMS) possess interesting magnetic behaviour arising due to the replacement of small amount of host anion by magnetic impurity. For the realization of DMS materials in practical applications, they should exhibit room temperature ferromagnetic ordering. When ferromagnetic metals are used as spin injectors, the polarization in the semiconductor tends to be quickly lost via spin-flip scattering. It is one of the primary challenges to create the ferromagnetic semiconductors due to the difficulty in the spin-injection into the semiconductors to form DMS at room temperature.
We studied the electronic and magnetic properties for the Mn-doped chalcopyrite (CH) AlAs, GaAs, ... more We studied the electronic and magnetic properties for the Mn-doped chalcopyrite (CH) AlAs, GaAs, and AlGaAs2 semiconductor by using the first-principles calculations. The chalcopyrite AlGaP2, AlGaAsP, and AlGaAs2 compounds have a semiconductor characters with a small band-gap. The interaction between Mn-3d and As-4p states at the Fermi level dominate rather than the other states. The ferromagnetic ordering of dopant Mn with high magnetic moment is induced due to the Mn(3d)-As(4p) strong coupling, which is attributed by the partially filled As-4p bands. The holes are mediated with keeping their 3d-electrons, therefore the ferromagnetic state is stabilized by this double-exchange mechanism. We noted that the ferromagnetic state with high magnetic moment is originated from the hybridized As(4p)-Mn(3d)-As(4p) interaction mediated by the holes-carrier.
The effects on the ferromagnetism of the O or Zn defect in Cu-doped ZnO with the concentration of... more The effects on the ferromagnetism of the O or Zn defect in Cu-doped ZnO with the concentration of 2.77-8.33% have been investigated by the first-principles calculations. The Cu doping in ZnO was calculated to be a kind of p-type ferromagnetic half-metals. When the Zn vacancy exists in Cu-doped ZnO, the Cu magnetic moment increases, while for the O vacancy it is reduced. It is noticeable that the ferromagnetic state was originated from the hybridized O(2p)-Cu(3d)-O(2p) chain formed through the p-d coupling. The carrier-mediated ferromagnetism by nitrogen or fluorine does not depend on their concentration.
The effects on the ferromagnetism of the O or Zn defect in Cu-doped ZnO with the concentration of... more The effects on the ferromagnetism of the O or Zn defect in Cu-doped ZnO with the concentration of 2.77-8.33% have been investigated by the first-principles calculations. The Cu doping in ZnO was calculated to be a kind of p-type ferromagnetic half-metals. When the Zn vacancy exists in Cu-doped ZnO, the Cu magnetic moment increases, while for the O vacancy it is reduced. It is noticeable that the ferromagnetic state was originated from the hybridized O(2p)-Cu(3d)-O(2p) chain formed through the p-d coupling. The carrier-mediated ferromagnetism by nitrogen or fluorine does not depend on their concentration.
We studied the effect on the electronic and magnetic properties of the N defect in clean and Cu-d... more We studied the effect on the electronic and magnetic properties of the N defect in clean and Cu-doped wurtzite III-nitrides by using the first-principles calculations. When it is doped two Cu atoms in the nearest neighboring sites, the system of AlN, GaN, or InN with the N vacancy is energetically more favorable than that without the N vacancy site. When the Cu concentration increases, the total magnetic moment of a supercell becomes small. The ferromagnetism of Cu atom is very low due to the weak 3d-3d coupling. It is noticeable that the spinexchange interaction between the Cu-3d and N defect states is important.
The electronic structure and magnetic properties of chalcopyrite (CH) AlGaAs 2 with dopant Mn at ... more The electronic structure and magnetic properties of chalcopyrite (CH) AlGaAs 2 with dopant Mn at 3.125 and 6.25 % concentrations are investigated using first-principles calculations. The CH AlGaAs 2 alloy is a p-type semiconductor with a small band-gap. The AlGaAs 2 :Mn shows that the ferromagnetic (FM) state is the most energetically favorable one. The Mn-doped AlGaAs 2 exhibits FM and strong half-metallic ground states.The spin polarized Al(Ga,Mn)As 2 state (Al-rich system) is more stable than the (Al,Mn)GaAs 2 state (Ga-rich system), which has a magnetic moment of 3.82m B /Mn. The interaction between Mn-3d and As-4p states at the Fermi level dominates the other states.The states at the Fermi level are mainlyAs-4p electrons, which mediate strong interaction between the Mn-3d and As-4p states. It is noticeable that the FM ordering of dopant Mn with high magnetic moment originates from the As(4p)-Mn(3d)-As(4p) hybridization, which is attributed to the partially unfilled As-4pbands. The high FM moment of Mn is due to the double-exchange mechanism mediated by valence-band holes.
The ferromagnetic and electronic structure for the Al x Ga 1-x P and Mn-doped AlGaP 2 was studied... more The ferromagnetic and electronic structure for the Al x Ga 1-x P and Mn-doped AlGaP 2 was studied by using the self-consistent full-potential linear muffin-tin orbital method. The lattice parameters of un-doped Al x Ga 1-x P (x = 0.25, 0.5, and 0.75) were optimized. The band-structure and the density of states of Mn-doped AlGaP 2 with or without the vacancy were investigated in detail. The P-3p states at the Fermi level dominate rather than the other states. Thus a strong interaction between the Mn-3d and P-3p states is formed. The ferromagnetic ordering of dopant Mn with high magnetic moment is induced due to the (Mn-3d)-(P-3p)-(Mn-3d) hybridization, which is attributed by the partially filled P-3p bands. The holes are mediated with keeping their 3d-characters, therefore the ferromagnetic state is stabilized by this double-exchange mechanism.
Uploads
Papers by Byung-Sub Kang